One mechanism by which fire and smoke may spread from one compartment of a structure to another is through passages or openings, often referred to as through-penetrations, in the walls, floors and ceiling. Such openings include, for example, cable access holes through which signal and power transmission cables pass.
Current methods used to prevent the spread of fire and passage of smoke through such openings include cutting two intumescent sheets to follow the contour of the penetrating cables, attaching them to each outer surface of the opening, and providing a bead of moldable intumescent putty along the perimeter of each sheet. While this technique is generally satisfactory for resisting the spread of fire and preventing the passage of smoke from one compartment to another, installation is labor intensive and time consuming. In addition, firestops fabricated in this manner do not lend themselves to repeated re-entry.
In addition, various bag-like devices, often referred to as pillows or bricks, are commercially available for fire stopping through-penetrations in wall and floor applications. Pillows are typically enclosed with polymeric film conforming to the shape of the filler material. Bricks typically comprise polyurethane foam with no additional film wrapping. These devices are secured in the opening by either a compression fit or friction between devices under slight compression. Compression fit requires the outer surfaces of the device to have low friction so devices can be slid past each other and easily positioned during installation. In wall applications, compression fit works well because gravity has little effect. In floor openings, however, sliding surfaces, which facilitate the installation process, are prone to sagging of the assembled firestop in all but the smallest openings. In addition, if one or more devices are removed from an opening to perform maintenance or to add or remove items from the opening, the remaining devices can more easily fall through the opening because the compressive force is relieved. Such installations must also be completely removed and replaced when cables or other items need to be added to or removed from an opening. In addition, floor applications often require a secondary reinforcement structure, such as a platform, grate or rack, to support the intumescent material in the opening and thereby prevent the bag-like device from falling through the opening. Such support structures, while accomplishing the desired function, add considerably to the time and expense of fire stopping the opening, and hinder re-entry of the opening.
Accordingly, there exists a need in the industry for a firestop article for fire stopping through-penetrations in floors and ceilings that is inexpensive, easy to install, allows the opening to be readily re-entered, and can effectively firestop openings in walls, floors, and ceilings without the need for a secondary support structure.